Semiconductor processing apparatus having lift and tilt mechanism

ABSTRACT

A lift/tilt assembly for use in a semiconductor wafer processing device is set forth. The lift/tilt assembly includes a linear guide comprising a fixed frame and a moveable frame. A nest for accepting a plurality of semiconductor wafers is rotatably connected to the moveable frame. The nest rotates between a wafer-horizontal orientation and a wafer-vertical orientation as it is driven with the movable frame by a motor that is coupled to the linear way. A lever connected to the nest provides an offset from true vertical for the nest when the nest is in the wafer-vertical orientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional patent application claimingpriority of U.S. Ser. No. 08/940,524, filed Sep. 30, 1997, nowabandoned, U.S. Ser. No. 08/680,056, filed Dec. 15, 1997, now abandoned,U.S. Ser. No. 08/991,062, filed Dec. 15, 1997, now U.S. Pat. No.6,091,498 and PCT/US98/00076, filed Jan. 5, 1998, all of which arehereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

In the production of semiconductor integrated circuits and othersemiconductor articles from semiconductor wafers, it is often necessaryto provide multiple metal layers on the wafer to serve as interconnectmetallization which electrically connects the various devices on theintegrated circuit to one another. Traditionally, aluminum has been usedfor such interconnects, however, it is now recognized that coppermetallization may be preferable.

The application of copper onto semiconductor wafers has; in particular,proven to be a great technical challenge. At this time coppermetallization has not achieved commercial reality due to practicalproblems of forming copper layers on semiconductor devices in a reliableand cost efficient manner. This is caused, in part, by the relativedifficulty in performing reactive ion etching or other selective removalof copper at reasonable production temperatures. The selective removalof copper is desirable to form patterned layers and provide electricallyconductive interconnects between adjacent layers of the wafer or otherwafer.

Because reactive ion etching cannot be efficiently used, the industryhas sought to overcome the problem of forming patterned layers of copperby using a damascene electroplating process where holes, more commonlycalled vias, trenches and other recesses are used in which the patternof copper is desired. In the damascene process, the wafer is firstprovided with a metallic seed layer which is used to conduct electricalcurrent during a subsequent metal electroplating step. The seed layer isa very thin layer of metal which can be applied using one or more ofseveral processes. For example, the seed layer of metal can be laid downusing physical vapor deposition or chemical vapor deposition processesto produce a layer on the order of 1000 angstroms thick. The seed layercan advantageously be formed of copper, gold, nickel, palladium, andmost or all other metals. The seed layer is formed over a surface whichis convoluted by the presence of the vias, trenches, or other devicefeatures which are recessed. This convoluted nature of the exposedsurface provides increased difficulties in forming the seed layer in auniform manner. Nonuniformities in the seed layer can result invariations in the electrical current passing from the exposed surface ofthe wafer during the subsequent electroplating process. This in turn canlead to nonuniformities in the copper layer which is subsequentlyelectroplated onto the seed layer. Such nonuniformities can causedeformities and failures in the resulting semiconductor device beingformed.

In damascene processes, the copper layer that is electroplated onto theseed layer is in the form of a blanket layer. The blanket layer isplated to an extent which forms an overlying layer, with the goal ofcompletely providing a copper layer that fills the trenches and vias andextends a certain amount above these features. Such a blanket layer willtypically be formed in thicknesses on the order of 10,000-15,000angstroms (1-1.5 microns).

The damascene processes also involve the removal of excess metalmaterial present outside of the vias, trenches or other recesses. Themetal is removed to provide a resulting patterned metal layer in thesemiconductor integrated circuit being formed. The excess platedmaterial can be removed, for example, using chemical mechanicalplanarization. Chemical mechanical planarization is a processing stepwhich uses the combined action of a chemical removal agent and anabrasive which grind and polish the exposed metal surface to removeundesired parts of the metal layer applied in the electroplating step.

Automation of the copper electroplating process has been elusive, andthere is a need in the art for improved semiconductor plating systemswhich can produce copper layers upon semiconductor articles which areuniform and can be produced in an efficient and cost-effective manner.More particularly, there is a substantial need to provide a copperplating system that is effectively and reliably automated.

BRIEF SUMMARY OF THE INVENTION

A lift/tilt assembly for use in a semiconductor wafer processing deviceis set forth. The lift/tilt assembly includes a linear guide comprisinga fixed frame and a moveable frame. A nest for accepting a plurality ofsemiconductor wafers is rotatably connected to the moveable frame. Thenest rotates between a wafer-horizontal orientation and a wafer-verticalorientation as it is driven with the movable frame by a motor that iscoupled to the linear guide. A lever connected to the nest provides anoffset from true vertical for the nest when the nest is in thewafer-vertical orientation.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an isometric view of the semiconductor wafer processing toolin accordance with the present invention.

FIG. 2 is a cross-sectional view taken along line 2—2 of thesemiconductor wafer processing tool shown in FIG. 1.

FIGS. 3-8 are a diagrammatic representation of a wafer cassetteturnstile and elevator of a preferred interface module of thesemiconductor wafer processing tool according to the present inventionoperating to exchange wafer cassettes between a hold position and anextraction position.

FIG. 9 is an isometric view of a preferred wafer cassette trayengageable with the turnstile of an interface module of thesemiconductor wafer processing tool.

FIGS. 10-15 illustrate one manner in which the processing tool may bemodularized to facilitate end-to-end connection of sequential processingunits.

FIGS. 16-19 illustrate a wafer conveying system in accordance with oneembodiment of the present invention.

FIGS. 20-25 illustrate a further wafer conveying system in accordancewith a further embodiment of the present invention.

FIG. 26 is a functional block diagram of an embodiment of a controlsystem of the semiconductor wafer processing tool.

FIG. 27 is a functional block diagram of a master/slave controlconfiguration of an interface module control subsystem for controlling awafer cassette interface module.

FIG. 28 is a functional block diagram of an interface module controlsubsystem coupled with components of a wafer cassette interface moduleof the processing tool.

FIG. 29 is a functional block diagram of a wafer conveyor controlsubsystem coupled with components of a wafer conveyor of the processingtool.

FIG. 30 is a functional block diagram of a wafer processing modulecontrol subsystem coupled with components of a wafer processing moduleof the processing tool.

FIG. 31 is a functional block diagram of a slave processor of theinterface module control subsystem coupled with components of a waferinterface module of the processing tool.

FIG. 32 is a functional block diagram of a slave processor of the waferconveyor control subsystem coupled with components of a wafer conveyorof the processing tool.

FIG. 33 is a cross-sectional view of a processing station for use inelectroplating a downward facing surface of a semiconductor wafer.

FIG. 34 illustrates a view of a lift/tilt assembly including a nestconnected to a linear guide.

FIG. 35 illustrates another view of a lift/tilt assembly including anest oriented in a wafer-vertical position and a loaded wafer cassette.

FIGS. 36-38 show section views of a lift/tilt assembly with the linearguide located at three translational locations.

FIG. 39 illustrates a view of an H-bar assembly that may be used with anest.

FIG. 40 shows the orientation of a tilt sensor connected to a nest.

FIG. 41 illustrates a laser mapping system that may be used to detectthe presence or absence of wafers in a wafer cassette.

FIG. 42 illustrates a view of a lift/tilt assembly in which the nest hasextended vertically past a laser mapping system.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a present preferred embodiment of the semiconductorwafer processing tool 10 is shown. The processing tool 10 may comprisean interface section 12 and processing section 14. Semiconductor wafercassettes 16 containing a plurality of semiconductor wafers, generallydesignated W, may be loaded into the processing tool 10 or unloadedtherefrom via the interface section 12. In particular, the wafercassettes 16 are preferably loaded or unloaded through at least one portsuch as first port 32 within a front outwardly facing wall of theprocessing tool 10. An additional second port 33 may be provided withinthe interface section 12 of the processing tool 10 to improve access andport 32 may be utilized as an input and port 33 may be utilized as anoutput.

Respective powered doors 35, 36 may be utilized to cover access ports32, 33 thereby isolating the interior of the processing tool 10 from theclean room. Each door 35, 36 may comprise two portions. The upperportions and lower portion move upward and downward, respectively, intothe front surface of the processing tool 10 to open ports 32, 33 andpermit access therein.

Wafer cassettes 16 are typically utilized to transport a plurality ofsemiconductor wafers. The wafer cassettes 16 are preferably oriented toprovide the semiconductor wafers therein in an upright or verticalposition for stability during transportation of the semiconductor wafersinto or out of the processing tool 10.

The front outwardly facing surface of the processing tool 10 mayadvantageously join a clean room to minimize the number of harmfulcontaminants which may be introduced into the processing tool 10 duringinsertion and removal of wafer cassettes 16. In addition, a plurality ofwafer cassettes 16 may be introduced into processing tool 10 or removedtherefrom at one time to minimize the opening of ports 32, 33 andexposure of the processing tool 10 to the clean room environment.

The interface section 12 joins a processing section 14 of the processingtool 10. The processing section 14 may include a plurality ofsemiconductor wafer processing modules for performing varioussemiconductor process steps. In particular, the embodiment of theprocessing tool 10 shown in FIG. 1 includes a plating module 20 defininga first lateral surface of the processing section 14. The processingsection 14 of the tool 10 may advantageously include additional modules,such as pre-wet module 22 and resist strip module 24, opposite theplating module 20.

Alternatively, other modules for performing additional processingfunctions may also be provided within the processing tool 10. Thespecific processing performed by processing modules of the processingtool 10 may be different or of similar nature. Various liquid andgaseous processing steps can be used in various sequences. Theprocessing tool 10 is particularly advantageous in allowing a series ofcomplex processes to be run serially in different processing modules setup for different processing solutions. All the processing can beadvantageously accomplished without human handling and in a highlycontrolled working space 11, thus reducing human operator handling timeand the chance of contaminating the semiconductor wafers.

The processing modules of the process tool 10 are preferably modular,interchangeable, stand-alone units. The processing functions performedby the processing tool 10 may be changed after installation of theprocessing tool 10 increasing flexibility and allowing for changes inprocessing methods. Additional wafer processing modules may be added tothe processing tool 10 or replace existing processing modules 19.

The processing tool 10 of the present invention preferably includes arear closure surface 18 joined with the lateral sides of the processingtool 10. As shown in FIG. 1, an air supply 26 may be advantageouslyprovided intermediate opposing processing modules of the processingsection 14. The interface section 12, lateral sides of the processingsection 14, closure surface 18, and air supply 26 preferably provide anenclosed work space 11 within the processing tool 10. The air supply 26may comprise a duct coupled with a filtered air source (not shown) forproviding clean air into the processing tool 10. More specifically, theair supply 26 may include a plurality of vents intermediate theprocessing modules 19 for introducing clean air into work space 11.

Referring to FIG. 16, exhaust ducts 58, 59 may be provided adjacent theframe 65 of a wafer transport unit guide 66 to remove the circulatedclean air and the contaminants therein. Exhaust ducts 58, 59 may becoupled with the each of the processing modules 19 for drawing suppliedclean air therethrough. In particular, clean air is supplied to theworkspace 11 of the processing tool 10 via air supply 26. The air may bedrawn adjacent the wafer transport units 62, 64 and into the processingmodules 19 via a plurality of vents 57 formed within a shelf or processdeck thereof by an exhaust fan (not shown) coupled with the output ofexhaust ducts 58, 59. Each processing module 19 within the processingtool 10 may be directly coupled with ducts 58, 59. The air may be drawnout of the ducts 58, 59 of the processing tool 10 through the rearclosant surface 18 or through a bottom of surface of the processing tool10. Providing an enclosed work space and controlling the environmentwithin the work space greatly reduces the presence of contaminants inthe processing tool 10.

Each of the processing modules may be advantageously accessed throughexterior panels of the respective modules forming the lateral side ofthe processing tool 10. The lateral sides of the processing tool 10 maybe adjacent a gray room environment. Gray rooms have fewer precautionsagainst contamination compared with the clean rooms. Utilizing thisconfiguration reduces plant costs while allowing access to theprocessing components and electronics of each wafer module of theprocessing tool 10 which require routine maintenance.

A user interface 30 may be provided at the outwardly facing frontsurface of the processing tool as shown in FIG. 1. The user interface 30may advantageously be a touch screen cathode ray tube control displayallowing finger contact to the display screen to effect various controlfunctions within the processing tool 10. An additional user interface 30may also be provided at the rear of the processing tool 10 or withinindividual processing modules so that processing tool 10 operation canbe effected from alternate locations about the processing tool 10.Further, a portable user interface 30 may be provided to permit anoperator to move about the processing tool 10 and view the operation ofthe processing components therein. The user interface 30 may be utilizedto teach specified functions and operations to the processing modules 19and semiconductor wafer transport units 62, 64.

Each module 20, 22, 24 within the processing tool 10 preferably includesa window 34 allowing visual inspection of processing tool 10 operationfrom the gray room. Further, vents 37 may be advantageously providedwithin a top surface of each processing module 20, 22, 24. Processingmodule electronics are preferably located adjacent the vents 37 allowingcirculating air to dissipate heat generated by such electronics.

The work space 11 within the interface section 12 and processing section14 of an embodiment of the processing tool 10 is shown in detail in FIG.2.

The interface section 12 includes two interface modules 38, 39 formanipulating wafer cassettes 16 within the processing tool 10. Theinterface modules 38, 39 receive wafer cassettes 16 through the accessports 32, 33 and may store the wafer cassettes 16 for subsequentprocessing of the semiconductor wafers therein. In addition, theinterface modules 38, 39 store the wafer cassettes for removal from theprocessing tool 10 upon completion of the processing of thesemiconductor wafers within the respective wafer cassette 16.

Each interface module 38, 39 may comprise a wafer cassette turnstile 40,41 and a wafer cassette elevator 42, 43. The wafer cassette turnstiles40, 41 generally transpose the wafer cassettes 16 from a stable verticalorientation to a horizontal orientation where access to thesemiconductor wafers is improved. Each wafer cassette elevator 42, 43has a respective wafer cassette support 47, 48 for holding wafercassettes 16. Each wafer cassette elevator 42, 43 is utilized toposition a wafer cassette 16 resting thereon in either a transferposition and extraction position. The operation of the wafer interfacemodules 38, 39 is described in detail below.

In a preferred embodiment of the present invention, the first waferinterface module 38 may function as an input wafer cassette interfacefor receiving unprocessed semiconductor wafers into the processing tool10. The second wafer interface module 39 may function as an output wafercassette interface for holding processed semiconductor wafers forremoval from the processing tool 10. Wafer transport units 62, 64 withinthe processing tool 10 may access wafer cassettes 16 held by eitherwafer interface module 38, 39. Such an arrangement facilitatestransferring of semiconductor wafers throughout the processing tool 10.

A semiconductor wafer conveyor 60 is shown intermediate processingmodules 20, 22, 24 and interface modules 38, 39 in FIG. 2. The waferconveyor 60 includes wafer transport units 62, 64 for transferringindividual semiconductor wafers W between each of the wafer interfacemodules 38, 39 and the wafer processing modules 19.

Wafer conveyor 60 advantageously includes a transport unit guide 66,such as an elongated rail, which defines a plurality of paths 68, 70 forthe wafer transport units 62, 64 within the processing tool 10. A wafertransport unit 62 on a first path 68 may pass a wafer transport unit 64positioned on a second path 70 during movement of the transport units62, 64 along transport guide 66. The processing tool 10 may includeadditional wafer transport units to facilitate the transfer ofsemiconductor wafers W between the wafer processing modules 20, 22, 24and wafer interface modules 38, 39.

More specifically, the second arm extension 88 may support asemiconductor wafer W via vacuum support 89. The appropriate wafertransport unit 62, 64 may approach a wafer support 401 by moving alongtransport unit guide 66. After reaching a proper location along guide66, the first extension 87 and second extension 88 may rotate toapproach the wafer support 401. The second extension 88 is positionedabove the wafer support 401 and subsequently lowered toward engagementfinger assemblies 409 on the wafer support 401.

The vacuum is removed from vacuum support 89, and finger assemblieswithin the processing modules grasp the semiconductor wafer W positionedtherein. Second extension 88 may be lowered and removed from beneath thesemiconductor wafer held by the wafer engagement fingers.

Following completion of processing of the semiconductor wafer within theappropriate processing module 20, 22, 24, a wafer transport unit 62, 64may retrieve the wafer and either deliver the wafer to anotherprocessing module 20, 22, 24 or return the wafer to a wafer cassette 16for storage or removal from the processing tool 10.

Each of the wafer transport units 62, 64 may access a wafer cassette 16adjacent the conveyor 60 for retrieving a semiconductor wafer from thewafer cassette 16 or depositing a semiconductor wafer therein. Inparticular, wafer transport unit 62 is shown withdrawing a semiconductorwafer W from wafer cassette 16 upon elevator 42 in FIG. 2. Morespecifically, the second extension 88 and vacuum support 89 connectedtherewith may be inserted into a wafer cassette 16 positioned in theextraction position. Second extension 88 and vacuum support 89 enterbelow the lower surface of the bottom semiconductor wafer W held bywafer cassette 16. A vacuum may be applied via vacuum support 89 oncesupport 89 is positioned below the center of the semiconductor wafer Wbeing removed. The second extension 88, vacuum support 89 andsemiconductor wafer W attached thereto may be slightly raised viatransfer arm elevator 90. Finally, first extension 87 and secondextension 88 may be rotated to remove the semiconductor wafer W from thewafer cassette 16. The wafer transport unit 62, 64 may thereafterdeliver the semiconductor wafer W to a wafer processing module 19 forprocessing.

Thereafter, wafer transport unit 62 may travel along path 68 to aposition adjacent an appropriate processing module 20, 22, 24 fordepositing the semiconductor wafer upon wafer processing support 401 forprocessing of the semiconductor wafer.

Interface Module

Referring to FIG. 3-FIG. 8, the operation of the interface module 38 isshown in detail. The following discussion is limited to wafer interfacemodule 38 but is also applicable to wafer interface module 39 inasmuchas each interface module 38, 39 may operate in substantially the samemanner.

Preferably, the first wafer interface module 38 and the second waferinterface module 39 may function as a respective semiconductor wafercassette 16 input module and output module of the processing tool 10.Alternately, both modules can function as both input and output. Morespecifically, wafer cassettes 16 holding unprocessed semiconductorswafers may be brought into the processing tool 10 via port 32 andtemporarily stored within the first wafer interface module 38 until thesemiconductor wafers are to be removed from the wafer cassette 16 forprocessing. Processed semiconductor wafers may be delivered to a wafercassette 16 within the second wafer interface module 39 via wafertransport units 62, 64 for temporary storage and/or removal from theprocessing tool 10.

The wafer interface modules 38, 39 may be directly accessed by each ofthe wafer transport units 62, 64 within the processing tool 10 fortransferring semiconductor wafers therebetween. Providing a plurality ofwafer cassette interface modules 38, 39 accessible by each wafertransport unit 62, 64 facilitates the transport of semiconductor wafersW throughout the processing tool 10 according to the present invention.

Each wafer interface module 38, 39 preferably includes a wafer cassetteturnstile 40 and a wafer cassette elevator 42 adjacent thereto. Theaccess ports 32, 33 are adjacent the respective wafer cassetteturnstiles 40, 41. Wafer cassettes 16 may be brought into the processingtool 10 or removed therefrom via ports 32, 33.

Wafer cassettes 16 are preferably placed in a vertical position ontocassette trays 50 prior to delivery into the processing tool 10.Cassette trays 50 are shown in detail in FIG. 9. The vertical positionof wafer cassettes 16 and the semiconductor wafers therein provides asecure orientation to maintain the semiconductor wafers within the wafercassette 16 for transportation.

Each wafer cassette turnstile 40, 41 preferably includes two saddles 45,46 each configured to hold a wafer cassette 16. Providing two saddles45, 46 enables two wafer cassettes 16 to be placed into the processingtool 10 or removed therefrom during a single opening of a respectiveaccess door 35, 36 thereby minimizing exposure of the workspace 11within the processing tool 10 to the clean room environment.

Each saddle 45, 46 includes two forks engageable with the cassette tray50. Saddles 45, 46 are powered by motors within the wafer cassetteturnstile shaft 49 to position the wafer cassette 16 in a horizontal orvertical orientation. The wafer cassettes 16 and semiconductor waferstherein are preferably vertically oriented for passage through theaccess ports 32, 33 and horizontally oriented in a transfer orextraction position to provide access of the wafers therein to the wafertransport units 62, 64.

The wafer cassette 16 held by wafer cassette turnstile 40 in FIG. 3,also referred to as wafer cassette 15, is in a hold position (alsoreferred to herein as a load position). The semiconductor wafers withina wafer cassette 16 in the hold position may be stored for subsequentprocessing. Alternatively, the semiconductor wafers within a wafercassette 16 in the hold position may be stored for subsequent removalfrom the processing tool 10 through an access port 32, 33.

Referring to FIG. 3, the wafer cassette 16 supported by the wafercassette elevator 42, also referred to as wafer cassette 17, is in anextraction or exchange position. Semiconductor wafers may either beremoved from or placed into a wafer cassette 16 positioned in theextraction position via a wafer transport unit 62, 64.

The wafer cassette turnstile 41 and wafer cassette elevator 42 mayexchange wafer cassettes 15, 17 to transfer a wafer cassette 17 havingprocessed semiconductor wafers therein from the extraction position tothe hold position for removal from the processing tool 10. Additionally,such an exchange may transfer a wafer cassette 15 having unprocessedsemiconductor wafers therein from the hold position to the extractionposition providing wafer transport units 62, 64 with access to thesemiconductor wafer therein.

The exchange of wafer cassettes 15, 17 is described with reference toFIG. 4-FIG. 8. Specifically, saddle 46 is positioned below a poweredshaft 44 of wafer cassette elevator 42. Shaft 44 is coupled with apowered wafer cassette support 47 for holding a wafer cassette 16. Shaft44 and wafer cassette support 47 attached thereto are lowered as shownin FIG. 4 and shaft 44 passes between the forks of saddle 46.

Referring to FIG. 5, a motor within shaft 44 rotates wafer cassettesupport 47 about an axis through shaft 44 providing the wafer cassette17 thereon in an opposing relation to the wafer cassette 15 held bywafer cassette turnstile 40. Both saddles 45, 46 of wafer cassetteturnstile 40 are subsequently tilted into a horizontal orientation asshown in FIG. 6. The shaft 44 of wafer cassette elevator 42 is nextlowered and wafer cassette 17 is brought into engagement with saddle 46as depicted in FIG. 7. The shaft 44 and wafer cassette support 47 arelowered an additional amount to clear rotation of wafer cassettes 16.Referring to FIG. 8, wafer cassette turnstile 40 rotates 180 degrees totranspose water cassettes 15, 17.

Wafer cassette 17 having processed semiconductor wafers therein is nowaccessible via port 32 for removal from the processing tool 10. Wafercassette 15 having unprocessed semiconductors therein is now positionedfor engagement with wafer cassette support 47. The transfer processsteps shown in FIG. 3-FIG. 8 may be reversed to elevate the wafercassette 15 into the extraction position providing access of thesemiconductor wafers to wafer transport units 62, 64.

FIG. 10 illustrates one manner in which the apparatus 10 may bemodularized. As illustrated, the apparatus 10 is comprised of aninput/output assembly 800, left and right processing modules 805, 810,wafer conveyor system 60, top exhaust assembly 820, and end panel 825.As illustrated, left and right processing modules 805 and 810 may besecured to one another about the wafer conveying system 60 to form aprocessing chamber having an inlet and 830 and an outlet 835. Aplurality of these processing modules may thus be secured in anend-to-end configuration to thereby provide an extended processingchamber capable of performing a substantially larger number of processeson each wafer or, in the alternative, process a larger number of wafersconcurrently. In such instances, the wafer conveying system 60 of oneapparatus 10 is programmed to cooperate with the wafer conveying system60 of one or more prior or subsequent conveying systems 60.

FIG. 11 illustrates one manner of arranging processing heads within theapparatus 10. In this embodiment, the left hand processing module 805 iscomprised of three processing heads that are dedicated to rinsing anddrying each wafer after electrochemical deposition and two processingheads for performing wetting of the wafers prior to electrochemicaldeposition. Generically, the left hand processing module 805 constitutesa support module having processing heads used in pre-processing andpost-processing of the wafers with respect to electrochemical copperdeposition. The right-hand module 810 generically constitutes a platingmodule and includes five reactor heads dedicated to electrochemicalcopper deposition. In the embodiment of FIG. 11, a wafer alignmentstation 850 is provided to ensure thickness proper orientation of eachwafer as it is processed in the apparatus. Wafer alignment may be basedupon sensing of registration marks or the like on each wafer.

FIGS. 12 and 13 illustrate embodiments of the left and right handprocessing modules 805 and 810, respectively. In these figures, theexterior portions of the respective housing have been removed therebyexposing various system components. Preferably, electronic componentssuch as power supplies, controllers, etc., are disposed in the upperportion of each of the processing modules 805 and 810, while movingcomponents and the like are disposed in a lower portion of each of theprocessing modules.

FIG. 14 is a perspective view of the input module 800 with its panelsremoved as viewed from the interior of apparatus 10. FIG. 15 provides asimilar view of the input module 800 with respect to the exterior ofapparatus 10. In the illustrated embodiment, the wafer alignment station850 and a wafer alignment controller 860 are provided in the inputmodule 800. A robot controller 865 used to control the wafer conveyingsystem 60 is also disposed therein. To keep track of the wafers as theyare processed, the input module 800 is provided with one or more wafermapping sensors 870 that sense the wafers present in each cassette.Other components in the input module 800 include the system controlcomputer 875 and a four-axis controller 880. The system control computer875 is generally responsible for coordinating all operations of theapparatus 10.

Semiconductor Wafer Conveyor

The processing tool 10 includes a semiconductor wafer conveyor 60 fortransporting semiconductor wafers throughout the processing tool 10.Preferably, semiconductor wafer conveyor 60 may access each wafercassette interface module 38, 39 and each wafer processing module 19within processing tool 10 for transferring semiconductor waferstherebetween. This includes processing modules from either side.

One embodiment of the wafer conveyor system 60 is depicted in FIG. 16.The wafer conveyor 60 generally includes a wafer transport unit guide 66which preferably comprises an elongated spine or rail mounted to frame65. Alternatively, transport unit guide 66 may be formed as a track orany other configuration for guiding the wafer transport units 62, 64thereon. The length of wafer conveyor 60 may be varied and is configuredto permit access of the wafer transport units 62, 64 to each interfacemodule 38, 39 and processing modules 20, 22, 24.

Wafer transport unit guide 66 defines the paths of movement 68, 70 ofwafer transport units 62, 64 coupled therewith. Referring to FIG. 16, aspine of transport unit guide 66 includes guide rails 63, 64 mounted onopposite sides thereof. Each semiconductor wafer transport unit 62, 64preferably engages a respective guide rail 63, 64. Each guide rail canmount one or more transport units 62, 64. Extensions 69, 75 may be fixedto opposing sides of guide 66 for providing stability of the transportunits 62, 64 thereagainst and to protect guide 66 from wear. Each wafertransport unit 62, 64 includes a roller 77 configured to ride along arespective extension 69, 75 of guide 66.

It is to be understood that wafer conveyor 60 may be formed in alternateconfigurations dependent upon the arrangement of interface modules 38,39 and processing modules 20, 22, 24 within the processing tool 10.Ducts 58, 59 are preferably in fluid communication with extensions fromeach wafer processing module 19 and an exhaust fan for removingcirculated air from the workspace 11 of the processing tool 10.

Each wafer transport unit 62, 64 is powered along the respective path68, 70 by a suitable driver. More specifically, drive operators 71, 74are mounted to respective sides of transport unit guide 66 to providecontrollable axial movement of wafer transport units 62, 64 along thetransport unit guide 66.

The drive operators 71, 74 may be linear magnetic motors for providingprecise positioning of wafer transport units 62, 64 along guide 66. Inparticular, drive operators 71, 74 are preferably linear brushlessdirect current motors. Such preferred driver operators 71, 74 utilize aseries of angled magnetic segments which magnetically interact with arespective electromagnet 79 mounted on the wafer transport units 62, 64to propel the units along the transport unit guide 66.

Cable guards 72, 73 may be connected to respective wafer transport units62, 64 and frame 65 for protecting communication and power cablestherein. Cable guards 72, 73 may comprise a plurality of interconnectedsegments to permit a full range of motion of wafer transport units 62,64 along transport unit guide 66.

As shown in FIG. 17, a first wafer transport unit 62 is coupled with afirst side of the spine of guide 66. Each wafer transport unit 62, 64includes a linear bearing 76 for engagement with linear guide rails 63,64. Further, the wafer transport units 62, 64 each preferably include ahorizontal roller 77 for engaging a extension 69 formed upon the spineof the guide 66 and providing stability.

FIG. 17 additionally shows an electromagnet 79 of the first wafertransport unit 62 mounted in a position to magnetically interact withdrive actuator 71. Drive actuator 71 and electromagnet 79 provide axialmovement and directional control of the wafer transport units 62, 64along the transport unit guide 66.

Semiconductor Wafer Transport Units

Preferred embodiments of the semiconductor wafer transport units 62, 64of the wafer conveyor 60 are described with reference to FIG. 18 andFIG. 19.

In general, each wafer transport unit 62, 64 includes a movable carriageor tram 84 coupled to a respective side of the transport unit guide 66,a wafer transfer arm assembly 86 movably connected to the tram 84 forsupporting a semiconductor wafer W, and a wafer transfer arm elevator 90for adjusting the elevation of the transfer arm assembly 86 relative totram 84.

Referring to FIG. 18, a cover 85 surrounds the portion of tram 84 facingaway from the transport unit guide 66. Tram 84 includes linear bearings76 for engagement with respective guide rails 63, 64 mounted totransport unit guide 66. Linear bearings 76 maintain the tram 84 in afixed relation with the transport unit guide 66 and permit axialmovement of the tram 84 therealong. A roller 77 engages a respectiveextension 69 for preventing rotation of tram 84 about guide rail 63, 64and providing stability of wafer transport unit 62. The electromagnet 79is also shown connected with the tram 84 in such a position tomagnetically interact with a respective transport unit 62, 64 driveactuator 71, 74.

A wafer transfer arm assembly 86 extends above the top of tram 84. Thewafer transfer arm assembly 86 may include a first arm extension 87coupled at a first end thereof with a shaft 83. A second arm extension88 may be advantageously coupled with a second end of the firstextension 87. The first arm extension 87 may rotate 360 degrees aboutshaft 83 and second arm extension 88 may rotate 360 degrees about axis82 passing through a shaft connecting first and second arm extensions87, 88.

Second extension 88 preferably includes a wafer support 89 at a distalend thereof for supporting a semiconductor wafer W during thetransporting thereof along wafer conveyor 60. The transfer arm assembly86 preferably includes a chamber coupled with the wafer support 89 forapplying a vacuum thereto and holding a semiconductor wafer W thereon.

Providing adjustable elevation of transfer arm assembly 86, rotation offirst arm extension 87 about the axis of shaft 83, and rotation ofsecond extension 88 about axis 82 allows the transfer arm 86 to accesseach semiconductor wafer holder 810 of all processing modules 19 andeach of the wafer cassettes 16 held by interface modules 38, 39 withinthe processing tool 10. Such access permits the semiconductor wafertransport units 62, 64 to transfer semiconductor wafers therebetween.

The cover 85 has been removed from the wafer transport unit shown inFIG. 19 to reveal a wafer transfer arm elevator 90 coupled with tram 84and transfer arm assembly 86. Transfer arm elevator 90 adjusts thevertical position of the transfer arm assembly 86 relative to the tram84 during the steps of transferring a semiconductor wafer between thewafer support 89 and one of a wafer holder 810 and the wafer cassette16.

The path position of the tram 84 of each wafer transport unit 62, 64along the transport unit guide 66 is precisely controlled using apositional indicating array, such as a CCD array 91 of FIG. 19. In oneembodiment of the processing tool 10, each semiconductor wafer holder810 within a processing module 19 has a corresponding light or otherbeam emitter 81 mounted on a surface of the processing module 19 asshown in FIG. 2 for directing a beam of light toward the transport unitguide 66. The light emitter 81 may present a continuous beam oralternatively may be configured to generate the beam as a wafertransport unit 62, 64 approaches the respective wafer holder 810.

The transfer arm assembly 86 includes an CCD array 91 positioned toreceive the laser beam generated by light emitter 81. A positionindicating array 91 on shaft 83 detects the presence of the light beamto determine the location of tram 84 along transport unit guide 66. Thepositional accuracy of the wafer transport unit position indicator ispreferably in the range less than 0.003 inch (approximately less than0.1 millimeter).

A second embodiment of a wafer transport unit 562 b is shown in FIGS.20-25 and is similarly provided with a movable carriage or tram 584coupled to a respective side of the transport unit guide 66, a wafertransfer arm assembly 586 movably connected to the tram 584 forsupporting a semiconductor wafer W, and a wafer transfer arm elevator590 for adjusting the elevation of the transfer arm assembly 586relative to tram 584. A cover 585 surrounds a portion of tram 584. Tram584 includes linear bearings 576 for engagement with respective guiderails 63, 64 mounted to transport unit guide 66. Linear bearings 576maintain the tram 584 in a fixed relation with the transport unit guide66 and permit axial movement of the tram 584 therealong. Theelectromagnet 579 magnetically interacts with the guide 66 to driveactuator 71, 74.

A wafer transfer arm assembly 586 extends above the top of tram 584. Thewafer transfer arm assembly 586 includes a first arm extension 587coupled at a first end thereof with a shaft 583. A second arm extension588, having a wafer support 589 for supporting the semiconductor waferW, may be advantageously coupled with a second end of the firstextension 587. The first arm extension 587 may rotate 360 degrees aboutshaft 583 and second arm extension 588 may rotate 360 degrees about axis582 passing through a shaft connecting first and second arm extensions587, 588.

As with the first embodiment, providing adjustable elevation of transferarm assembly 586, rotation of first arm extension 587 about the axis ofshaft 583, and rotation of second extension 588 about axis 582 permitsthe semiconductor wafer transport units 562 a, 562 b to transfersemiconductor wafers therebetween.

As shown in FIG. 21, cover 585 has been removed from the wafer transportunit 562 b, revealing a wafer transfer arm elevator 590 coupled withtram 584 and transfer arm assembly 586. Transfer arm elevator 590adjusts the vertical position of the transfer arm assembly 586 relativeto the tram 584 during a transfer of a semiconductor wafer.

In the second embodiment of the wafer transport units 562 a, 562 b, afiber optic communication path, such as a fiber optic filament, replaceswires 72, 73 to the wafer transport units through a digital-to-analogconverter board 540 on each of the wafer transport units 562 a, 562 b.The use of fiber optics as opposed to wire harnesses lowers the inertialmass of the transport units 562 a, 562 b and improves reliability. Onemanner of implementing circuitry for such a fiber optic communicationlink and corresponding control at the transport units is set forth inthe schematics of FIGS. 34-64. Preferably, such communications takeplace between the transfer unit and the system controller 875.

The path and operational position of the tram 584 of each wafertransport unit 562 a, 562 b along the transport unit guide 66 isprecisely controlled using a combination of encoders to provide positioninformation on the position of the tram 584, transfer arm assembly 586and second extension 588 in three-axis space. An absolute encoder, theposition of which is shown at 591, is located in the elevator 590. Anabsolute encoder, TPOW, is shown at 592, located in the base motor 593of the shaft 583. An absolute encoder, TPOW, is shown at 594, located inthe shaft 583. Wrist absolute encoder, the position of which is shown at595, is located at the distal end of transfer arm assembly 586. An elbowabsolute encoder, TPOWISA, 597 is provided at the base of the shaft 583.Lift absolute encoder 596 is located along the base motor 593. A linearencoder 598, head rail encoder 599 and track CDD array absolute encoder541 are located on the base plate 203 of the base of tram 584, thelatter located for sensing the beam emitter 81 mounted on a surface ofthe processing module 19 as shown in FIG. 2 and discussed above. Theforegoing allows precise and reliable positional accuracy.

Mounting of the wafer transport units is shown in FIG. 22. Asillustrated, a wafer conveyor 560 includes a wafer transport unit guide566 which comprises an elongated spine or rail mounted to frame 565.Wafer transport unit guide 566 defines the paths of movement 568, 570 ofwafer transport units 544 a, 544 b. A spine of transport unit guide 566includes upper guide rails 563 a, 564 a and lower guide rails 563 b, 564b mounted on opposite sides thereof. Each semiconductor wafer transportunit 544 a, 544 b preferably engages each of the respective upper guiderails 563 a, 564 b and lower guide rails 563 b, 564 b. Each of the pairof upper and lower guide rails can mount one or more transport units 544a, 544 b.

Each wafer transport unit 544 a, 544 b is also powered along therespective path 568, 570 by drive operators 571, 574 mounted torespective sides of transport unit guide 66 to provide controllableaxial movement of wafer transport units 544 a, 544 b along the transportunit guide 566. The drive operators 571, 574 may be linear magneticmotors for providing precise positioning of wafer transport units 544 a,544 b along guide 566, and are again preferably linear brushless directcurrent motors utilizing a series of angled magnetic segments whichmagnetically interact with a respective electromagnet 579 mounted oneach of the wafer transport units 544 a, 544 b to propel the units alongthe transport unit guide 566.

Fiber optic cable guards 572, 573 provide communication with therespective wafer transport units 544 a, 544 b and protect fiber opticcables located therein. Cable guards 572, 573 may comprise a pluralityof interconnected segments to permit a full range of motion of wafertransport units 544 a, 544 b along transport unit guide 566.

As shown in FIG. 22, wafer transport units 544 a, 544 b are coupledalong each side of the spine of guide 566. Each wafer transport unit 544a, 544 b includes an upper linear bearing 576 a for engagement withupper linear guide rails 563 a, 564 a, respectively. Further, each wafertransport units 544 a, 544 b includes a lower linear bearing 576 bengaging the lower linear guide rails 563 b, 564 b, providing stabilityand more equal distribution of the weight loads upon the rails. Withreference to FIGS. 22-24, the upper and lower linear bearing 576 a, 576b also provides a means by which the vertical axis of the wafer transferarm assembly 586 extending above the top of tram 584 may be adjusted. Itis important that the transfer arm assembly 586 rotate in a plane asclose as possible to the absolute horizontal plane during the transferof wafers within the processing tool 10. To this end, the lower elbowhousing 210 of the transfer arm assembly, shown in FIG. 25, mounted tothe base plate 203 of the transport unit 544 a is provided with a tiltadjustment.

The lower elbow housing 210 is mounted to a base plate 211, as seen inFIGS. 21, 23 and 24 through upper mounting screws 212 and lower mountingscrews 214. The base plate 211 is in turn fastened to the elevator motor590 to raise or lower the transfer arm assembly 586, better seen in FIG.25. As seen in FIG. 26, positioned laterally between the upper mountingscrews 212 are embossed pivots 216 on the base plate 211 that engage acorresponding, yet slightly smaller, lateral groove 218 on the lowerelbow housing 210. The pivots 216 are preferably sized, relative thelateral groove 218 to provide a clearance between the base plate 211 andthe lower elbow housing 210 so that about 0.95 degrees of tilt isavailable between the two. In combination with one or more levelingscrews 220 and the upper and lower mounting screws 212, 214, the angularorientation of the lower elbow housing 210, and the attached transferarm assembly 586, can be adjusted and fixed to provide rotation of thetransfer arm assembly 586 as close as possible within the absolutehorizontal plane during the transfer of wafers within the processingtool 10.

Also, compliant attachment of the lower linear bearing guides 576 b isimportant to smooth operation of the wafer transport unit 544 a, 544 balong the guide 566. Providing such compliant attachment, preferablyallowing 0.100 inch of float, at the lower gearing guides 576 b isobtained by use of a compliant fastening technique. A float pin 221 ispositioned about mounting screw 222, with an O-ring 223, preferablyVITON, positioned about the float pin. When installed within shoulderedcounterbore 224 of the base plate 203 into tapped hole 227 of lowerbearing guide 576 b, as shown in FIG. 28, the screw 222 bears against aflange 225 of the float pin 221, which in turn bears against the O-ring223. The O-ring 223 then bears against the shoulder 226 of thecounterbore. However, even when the screw 222 is tightened, relativemotion is allowed between the lower bearing guide 576 b and the baseplate 203 to facilitate smooth motion over the entire guide 566.

Control System

Referring to FIG. 26, there is shown one embodiment of the controlsystem 100 of the semiconductor wafer processing tool 10. Asillustrated, the control system 100 generally includes at least onegrand master controller 101 for controlling and/or monitoring theoverall function of the processing tool 10.

The control system 100 is preferably arranged in a hierarchialconfiguration. The grand master controller 101 includes a processorelectrically coupled with a plurality of subsystem control units asshown in FIG. 26. The control subsystems preferably control and monitorthe operation of components of the corresponding apparatus (i.e., waferconveyor 60, processing modules 20, 22, 24, interface modules 38, 39,etc.). The control subsystems are preferably configured to receiveinstructional commands or operation instructions such as software codefrom a respective grand master control 101, 102. The control subsystems110, 113-119 preferably provide process and status information torespective grand master controllers 101, 102.

More specifically, the grand master control 101 is coupled with aninterface module control 110 which may control each of the semiconductorwafer interface modules 38, 39. Further, grand master control 101 iscoupled with a conveyor control 113 for controlling operations of thewafer conveyor 60 and a plurality of processing module controls 114, 115corresponding to semiconductor wafer processing modules 20, 22 withinthe processing tool 10. The control system 100 of the processing tool 10according to the present disclosure may include additional grand mastercontrollers 102 as shown in FIG. 26 for monitoring or operatingadditional subsystems, such as additional wafer processing modules viaadditional processing module control 119. Four control subsystems may bepreferably coupled with each grand master controller 101, 102. The grandmaster controllers 101, 102 are preferably coupled together and each maytransfer process data to the other.

Each grand master controller 101, 102 receives and transmits data to therespective modular control subsystems 110-119. In a preferred embodimentof the control system 100, a bidirectional memory mapped device isprovided intermediate the grand master controller and each modularsubsystem connected thereto. In particular, memory mapped devices 160,161, 162 are provided intermediate the grand master controller 101 andmaster controllers 130, 131, 132 within respective interface modulecontrol 110, wafer conveyor control 113 and processing module control114.

Each memory mapped device 150, 160-162 within the control system 100 ispreferably a dual port RAM provided by Cypress for a synchronouslystoring data. In particular, grand master controller 101 may write datato a memory location corresponding to master controller 130 and mastercontroller 130 may simultaneously read the data. Alternatively, grandmaster controller 101 may read data from mapped memory device beingwritten by the master controller 130. Utilizing memory mapped devices160-161 provides data transfer at processor speeds. Memory mapped device150 is preferably provided intermediate user interface 30 and the grandmaster controllers 101, 102 for transferring data therebetween.

A user interface 30 is preferably coupled with each of the grand mastercontrollers 101, 102. The user interface 30 may be advantageouslymounted on the exterior of the processing tool 10 or at a remotelocation to provide an operator with processing and status informationof the processing tool 10. Additionally, an operator may input controlsequences and processing directives for the processing tool 10 via userinterface 30. The user interface 30 is preferably supported by a generalpurpose computer within the processing tool 10. The general purposecomputer preferably includes a 486 100 MHz processor, but otherprocessors may be utilized.

Each modular control subsystem, including interface module control 10,wafer conveyor control 113 and each processing module control 114-119,is preferably configured in a master/slave arrangement. The modularcontrol subsystems 110, 113-119 are preferably housed within therespective module such as wafer interface module 38, 39, wafer conveyor60, or each of the processing modules 20, 22, 24. The grand mastercontroller 101 and corresponding master controllers 130, 131, 132coupled therewith are preferably embodied on a printed circuit board orISA board mounted within the general purpose computer supporting userinterface 30. Each grand master controller 101, 102 preferably includesa 68EC000 processor provided by Motorola and each master controller 130and slave controller within control system 100 preferably includes a80251 processor provided by Intel.

Each master controller 130, 131, 132 is coupled with its respectiveslave controllers via a data link 126, 127, 129 as shown in FIG. 27-FIG.30. Each data link 126, 127, 129 preferably comprises an optical datamedium such as Optilink provided by Hewlett Packard. However, data links126, 127, 129 may comprise alternate data transfer media.

Referring to FIG. 27, the master/slave control subsystem for theinterface module control 110 is illustrated. Each master and relatedslave configuration preferably corresponds to a single module (i.e.,interface, conveyor, processing) within the processing tool 10. However,one master may control or monitor a plurality of modules. Themaster/slave configuration depicted in FIG. 27 and corresponding to theinterface module control 110 may additionally apply to the other modularcontrol subsystems 113, 114, 115.

The grand master controller 101 is connected via memory mapped device160 to a master controller 130 within the corresponding interface modulecontrol 110. The master controller 130 is coupled with a plurality ofslave controllers 140, 141, 142. Sixteen slave controllers may bepreferably coupled with a single master controller 130-132 and eachslave controller may be configured to control and monitor a single motoror process component, or a plurality of motors and process components.

The control system 100 of the processing tool 10 preferably utilizesflash memory. More specifically, the operation instructions or programcode for operating each master controller 130-132 and slave controller140-147 within the control system 100 may be advantageously storedwithin the memory of the corresponding grand master controller 101, 102.Upon powering up, the grand master controller 101, 102 may poll thecorresponding master controllers 130-132 and download the appropriateoperation instruction program to operate each master controller 130-132.Similarly, each master controller 130-132 may poll respective slavecontrollers 140-147 for identification. Thereafter, the mastercontroller 130-132 may initiate downloading of the appropriate programfrom the grand master controller 101, 102 to the respective slavecontroller 140-147 via the master controller 130-132.

Each slave controller may be configured to control and monitor a singlemotor or a plurality of motors within a corresponding processing module19, interface module 38, 39 and wafer conveyor 60. In addition, eachslave controller 140-147 may be configured to monitor and controlprocess components 184 within a respective module 19. Any one slavecontroller, such as slave controller 145 shown in FIG. 36, may beconfigured to control and/or monitor servo motors and process components184.

Each slave controller includes a slave processor which is coupled with aplurality of port interfaces. Each port interface may be utilized forcontrol and/or monitoring of servo motors and process components 184.For example, a port may be coupled with a servo controller card 176which is configured to operate a wafer transfer unit 62 a, 62 b. Theslave processor 171 may operate the wafer transfer unit 62 a, 62 b viathe port and servo controller 176. More specifically, the slaveprocessor 171 may operate servo motors within the wafer transfer unit 62a, 62 b and monitor the state of the motor through the servo controller176.

Alternatively, different slave controllers 140, 141 may operatedifferent components within a single processing tool device, such asinterface module 38. More: specifically, the interface module control110 and components of the interface module 38 are depicted in FIG. 32.Slave controller 140 may operate turnstile motor 185 and monitor theposition of the turnstile 40 via incremental turnstile encoder 190.Slave controller 140 is preferably coupled with the turnstile motor 185and turnstile encoder 190 via a servo control card (shown in FIG. 35).Slave controller 141 may operate and monitor saddle 45 of the turnstile40 by controlling saddle motor 186 and monitoring saddle encoder 191 viaa servo control card.

A port of a slave processor may be coupled with an interface controllercard 180 for controlling and monitoring process components within arespective processing module 19. For example, a flow sensor 657 mayprovide flow information of the delivery of processing fluid to aprocessing bowl within the module. The interface controller 180 isconfigured to translate the data provided by the flow sensors 657 orother process components into a form which may be analyzed by thecorresponding slave processor 172. Further, the interface controller 180may operate a process component, such as a flow controller 658,responsive to commands from the corresponding slave processor 172.

One slave controller 140-147 may contain one or more servo controllerand one or more interface controller coupled with respective ports ofthe slave processor 170-172 for permitting control and monitorcapabilities of various component motors and processing components froma single slave controller.

Alternatively, a servo controller and interface controller may eachcontain an onboard processor for improving the speed of processing andoperation. Data provided by an encoder or process component to the servocontroller or interface controller may be immediately processed by theon board processor which may also control a respective servo motor orprocessing component responsive to the data. In such a configuration,the slave processor may transfer the data from the interface processoror servo controller processor to the respective master controller andgrand master controller.

Conveyer Control Subsystem

The conveyor control subsystem 113 for controlling and monitoring theoperation of the wafer conveyor 60 and the wafer transport units 62 a,62 b or 562 a, 562 b or 544 a, 544 b therein is shown in FIG. 29. Ingeneral, a slave controller 143 of conveyor control 113 is coupled withdrive actuator 71 for controllably moving and monitoring a wafertransport unit 62 a along the guide 66. Further, slave controller 143may operate transfer arm assembly 86 of the wafer transport unit 62 a or562 a or 544 a and the transferring of semiconductor wafers thereby.Similarly, slave controller 144 may be configured to operate wafertransport unit 62 b or 562 b or 544 b and drive actuator 74.

The interfacing of slave controller 143 and light detector 91, driveactuator 71, linear encoder 196 and wafer transport unit 62 a is shownin detail in FIG. 36. The slave processor 171 of slave controller 143 ispreferably coupled with a servo controller 176. Slave processor 171 maycontrol the linear position of wafer transport unit 62 a by operatingdrive actuator 71 via servo controller 176. Light detector 91 mayprovide linear position information of the wafer transport unit 62 aalong guide 66. Additionally, a linear encoder 196 may also be utilizedfor precisely monitoring the position of wafer transport unit 62 alongguide 66.

The conveyor slave processor 171 may also control and monitor theoperation of the transfer arm assembly 86 of the corresponding wafertransport unit 62 a. Specifically, the conveyor processor 171 may becoupled with a transfer arm motor 194 within shaft 83 for controllablyrotating the first and second arm extensions 87, 88. An incrementaltransfer arm rotation encoder 197 may be provided within the shaft 83 ofeach wafer transport unit 62 a for monitoring the rotation of transferarm assembly 86 and providing rotation data thereof to servo controller176 and slave processor 171.

Slave controller 143 may be advantageously coupled with transfer armelevation motor 195 within elevator 90 for controlling the elevationalposition of the transfer arm assembly 86. An incremental transfer armelevation encoder 198 may be provided within the transfer arm elevatorassembly 90 for monitoring the elevation of the transfer arm assembly86.

In addition, conveyor slave controller 143 may be coupled with an airsupply control valve actuator (not shown) via an interface controllerfor controlling a vacuum within wafer support 89 for selectivelysupporting a semiconductor wafer thereon.

Absolute encoders 199 may be provided within the wafer conveyor 60,interface modules 38, 39 and processing modules 19 to detect extremeconditions of operation and protect servo motors therein. For example,absolute encoder 199 may detect a condition where the transfer armassembly 86 has reached a maximum height and absolute encoder 199 mayturn off elevator 90 to protect transfer arm elevator motor 195.

A similar approach may be used for the fiber optic signal communicationsystem of the second and third embodiments of the wafer transfer units562 a, 562 b and 544 a, 544 b, respectively. Particular, encoder 591located in the elevator 590, encoder 592 located in the base motor 593of the shaft 583, encoder 594 located in the shaft 583, wrist absoluteencoder 595 located at the distal end of transfer arm assembly 586 andelbow absolute encoder 597 located at the base of the shaft 583 providethe rotational input of rotational encoder 193 of FIG. 35. Likewise,lift absolute encoder 596 located along the base motor 593, linearencoder 598, head rail encoder 599 and track CDD array absolute encoder541 provide inputs for the lift encoder 192 and absolute encoder 199 ofFIG. 35, respectively.

Processing Module Control

The control system 100 preferably includes a processing module controlsubsystem 114-116 corresponding to each wafer processing module 20, 22,24 within the processing tool 10 according to the present disclosure.The control system 100 may also include additional processing modulecontrol subsystem 119 for controlling and/or monitoring additional waferprocessing modules 19.

Respective processing module controls 114, 115, 116 may control andmonitor the transferring of semiconductor wafers W between acorresponding wafer holder 810 and wafer transport unit 62 a, 62 b or562 a, 562 b or 544 a, 544 b. Further, processing module controls 114,115, 116 may advantageously control and/or monitor the processing of thesemiconductor wafers W within each processing module 20, 22, 24.

Referring to FIG. 30, a single slave controller 147 may operate aplurality of wafer holders 401 c-401 e within a processing module 20.Alternatively, a single slave controller 145, 146 may operate andmonitor a single respective wafer holder 401 a, 401 b. An additionalslave controller 148 may be utilized to operate and monitor all processcomponents 184 (i.e., flow sensors, valve actuators, heaters,temperature sensors) within a single processing module 19. Further, asshown in FIG. 37, a single slave controller 145 may operate and monitora wafer holder 410 and process components 184.

In addition, a single slave controller 145-148 may be configured tooperate and monitor one or more wafer holder 401 and processingcomponents 184. The interfacing of a slave controller 145 to both awafer holder 401 and process components are shown in the control systemembodiment in FIG. 37. In particular, a servo controller 177 andinterface controller 180 may be coupled with respective ports connectedto slave processor 172 of slave controller 145. Slave processor 172 mayoperate and monitor a plurality of wafer holder components via servocontroller 177. In particular, slave processor 172 may operate liftmotor 427 for raising operator arm 407 about lift drive shaft 456. Anincremental lift motion encoder 455 may be provided within a waferholder 401 to provide rotational information of lift arm 407 to therespective slave processor 172 or a processor within servo controller177. Slave processor 172 may also control a rotate motor 428 withinwafer holder 401 for rotating a processing head 406 about shafts 429,430 between a process position and a semiconductor wafer transferposition. Incremental rotate encoder 435 may provide rotationalinformation regarding the processing head 406 to the corresponding slaveprocessor 172.

Spin motor 480 may also be controlled by a processor within servocontroller 177 or slave processor 172 for rotating the wafer holder 478during processing of a semiconductor wafer W held thereby. Anincremental spin encoder 498 is preferably provided to monitor the rateof revolutions of the wafer holder 478 and supply the rate informationto the slave processor 172.

Plating module control 114 advantageously operates the fingertips 414 ofthe wafer holder 478 for grasping or releasing a semiconductor wafer. Inparticular, slave processor 172 may operate a valve via pneumatic valveactuator 201 for supplying air to pneumatic piston 502 for actuatingfingertips 414 for grasping a semiconductor wafer. The slave controller145 within the plating module control 114 may thereafter operate thevalve actuator 201 to remove the air supply thereby disengaging thefingertips 414 from the semiconductor wafer. Slave processor 172 mayalso control the application of electrical current through the fingerassembly 824 during the processing of a semiconductor wafer by operatingrelay 202.

The processing module controls 114, 115, 116 preferably operate andmonitor the processing of semiconductor wafers within the correspondingwafer processing modules 20, 22, 24 via instrumentation or processcomponents 184.

Referring to FIG. 33, the control operation for the plating processingmodule 20 is described. Generally, slave processor 172 monitors and/orcontrols process components 184 via interface controller 180. Slaveprocessor 172 within the plating module control 114 operates pump 605 todraw processing solution from the process fluid reservoir 604 to thepump discharge filter 607. The processing fluid passes through thefilter, into supply manifold 652 and is delivered via bowl supply linesto a plurality of processing plating bowls wherein the semiconductorwafers are processed. Each bowl supply line preferably includes a flowsensor 657 coupled with the plating processing module control 114 forproviding flow information of the processing fluid thereto. Responsiveto the flow information, the slave processor 172 may operate an actuatorof flow controller 658 within each bowl supply line to control the flowof processing fluid therethrough. Slave processor 172 may also monitorand control a back pressure regulator 656 for maintaining apredetermined pressure level within the supply manifold 652. Thepressure regulator 656 may provide pressure information to the slaveprocessor 172 within the plating processing control module 114.

Similarly, processing module control subsystems 115, 116 may beconfigured to control the processing of semiconductor wafers within thecorresponding prewet module 22 and resist module 24.

Interface Module Control

Each interface module control subsystem 110 preferably controls andmonitors the operation of wafer interface modules 38, 39. Morespecifically, interface module control 110 controls and monitors theoperation of the wafer cassette turnstiles 40, 41 and elevators 42, 43of respective semiconductor wafer interface modules 38, 39 to exchangewafer cassettes 16.

Slave processor 170 within slave controller 140 of interface modulecontrol 110 may operate and monitor the function of the interfacemodules 38, 39. In particular, slave processor 170 may operate doors 35,36 for providing access into the processing tool 10 via ports 32, 33.Alternatively, master control 100 may operate doors 35, 36.

Referring to FIG. 31, an embodiment of the interface module controlportion for controlling wafer interface module 38 is discussed. Inparticular, the slave processor 170 is coupled with servo controller175. Either slave processor 170 or a processor on board servo controller175 may operate the components of interface module 38. In particular,slave processor 170 may control turnstile motor 185 for operating rotatefunctions of turnstile 40 moving wafer cassettes 16 between a loadposition and a transfer position. Incremental turnstile encoder 190monitors the position of turnstile 40 and provides position data toslave processor 170. Alternatively, servo controller 175 may include aprocessor for reading information from turnstile encoder 190 andcontrolling turnstile motor 185 in response thereto. Servo controller175 may alert slave processor 170 once turnstile 40 has reaches adesired position.

Each wafer cassette turnstile 40 includes a motor for controlling thepositioning of saddles 45, 46 connected thereto. The slave processor 170may control the position of saddles 45, 46 through operation of theappropriate saddle motor 186 to orient wafer cassettes 16 attachedthereto in one of a vertical and horizontal orientation. Incrementalsaddle encoders 191 are preferably provided within each wafer cassetteturnstile 40 for providing position information of the saddles 45, 46 tothe respective slave processor 170.

Either slave processor 170 or servo controller 175 may be configured tocontrol the operation of the wafer cassette elevator 42 for transferringa wafer cassette 16 between either the exchange position and theextraction position. The slave processor 170 may be coupled with anelevator lift motor 187 and elevator rotation motor 188 for controllingthe elevation and rotation of elevator 42 and elevator support 47.Incremental lift encoder 192 and incremental rotation encoder 193 maysupply elevation and rotation information of the elevator 42 and support47 to slave processor 170.

Absolute encoders 199 may be utilized to notify slave processor ofextreme conditions such as when elevator support 47 reaches a maximumheight. Elevator lift motor 187 may be shut down in response to thepresence of an extreme condition by absolute encoder 199.

Wafer Cassette Tray

A wafer cassette tray 50 for holding a wafer cassette 16 is shown indetail in FIG. 9. Each cassette tray 50 may include a base 51 and anupright portion 54 preferably perpendicular to the base 51. Two lateralsupports 52 may be formed on opposing sides of the base 51 and extendupward therefrom. Lateral supports 52 assist with maintaining wafercassettes 16 thereon in a fixed position during the movement, rotationand exchange of wafer cassettes 16. Each lateral support 52 contains agroove 53 preferably extending the length thereof configured to engagewith the forks of saddles 45, 46.

The wafer cassette trays 50 are preferably utilized during the handlingof wafer cassettes 16 within the wafer cassette interface modules 38, 39where the wafer cassettes 16 are transferred from a load position to anextraction position providing access of the semiconductor wafers W towafer transport units 62, 64 within the conveyor 60.

Electroplating Station

FIG. 33 shows principal components of a second semiconductor processingstation 900 is specifically adapted and constructed to serve as anelectroplating station. The two principal parts of processing station900 are the wafer rotor assembly, shown generally at 906, and theelectroplating bowl assembly 303.

Electroplating Bowl Assembly 303

FIG. 33 shows an electroplating bowl assembly 303. The process bowlassembly consists of a process bowl or plating vessel 316 having anouter bowl side wall 317, bowl bottom 319, and bowl rim assembly 917.The process bowl is preferably circular in horizontal cross-section andgenerally cylindrical in shape although other shapes may be possible.

The bowl assembly 303 includes a cup assembly 320 which is disposedwithin a process bowl vessel 317. Cup assembly 320 includes a fluid cupportion 321 holding the chemistry for the electroplating process. Thecup assembly also has a depending skirt 371 which extends below the cupbottom 323 and may have flutes open therethrough for fluid communicationand release of any gas that might collect as the chamber below fillswith liquid. The cup is preferably made from polypropylene or othersuitable material.

A lower opening in the bottom wall of the cup assembly 320 is connectedto a polypropylene riser tube 330 which is adjustable in height relativethereto by a threaded connection. A first end of the riser tube 330 issecured to the rear portion of an anode shield 393 which supports anode334. A fluid inlet line 325 is disposed within the riser tube 330. Boththe riser tube 330 and the fluid inlet line are secured with theprocessing bowl assembly 303 by a fitting 362. The fitting 362 canaccommodate height adjustment of both the riser tube and line 325. Assuch, the connection between the fitting 362 and the riser tube 330facilitates vertical adjustment of the anode position. The inlet line325 is preferably made from a conductive material, such as titanium, andis used to conduct electrical current to the anode 324, as well assupply fluid to the cup.

Process fluid is provided to the cup through fluid inlet line 325 andproceeds therefrom through fluid inlet openings 324. Plating fluid thenfills the chamber 904 through opening 324 as supplied by a plating fluidpump (not shown) or other suitable supply.

The upper edge of the cup side wall 322 forms a weir which limits thelevel of electroplating solution within the cup. This level is chosen sothat only the bottom surface of wafer W is contacted by theelectroplating solution. Excess solution pours over this top edgesurface into an overflow chamber 345. The level of fluid in the chamber345 is preferably maintained within a desired range for stability ofoperation by monitoring the fluid level with appropriate sensors andactuators. This can be done using several different outflowconfigurations. A preferred configuration is to sense a high levelcondition using an appropriate sensor and then drain fluid through adrain line as controlled by a control valve. It is also possible to usea standpipe arrangement (not illustrated), and such is used as a finaloverflow protection device in the preferred plating station. Morecomplex level controls are also possible.

The outflow liquid from chamber 345 is preferably returned to a suitablereservoir. The liquid can then be treated with additional platingchemicals or other constituents of the plating or other process liquidand used again.

In the preferred uses according to this invention, the anode 334 is aconsumable anode used in connection with the plating of copper or othermetals onto semiconductor materials. The specific anode will varydepending upon the metal being plated and other specifics of the platingliquid being used. A number of different consumable anodes which arecommercially available may be used as anode 334.

FIG. 33 also shows a diffusion plate 375 provided above the anode 334for providing a more even distribution of the fluid plating bath acrossthe Wafer W. Fluid passages are provided over all or a portion of thediffusion plate 375 to allow fluid communication therethrough. Theheight of the diffusion plate is adjustable using diffuser heightadjustment mechanisms 386.

The anode shield 393 is secured to the underside of the consumable anode334 using anode shield fasteners 394 to prevent direct impingement bythe plating solution as the solution passes into the processing chamber904. The anode shield 393 and anode shield fasteners 394 are preferablymade from a dielectric material, such as polyvinylidene fluoride orpolypropylene. The anode shield is advantageously about 25 millimetersthick, more preferably about 3 millimeters thick.

The anode shield serves to electrically isolate and physically protectthe back side of the anode. It also reduces the consumption of organicplating liquid additives. Although the exact mechanism may not be knownat this time, the anode shield is believed to prevent disruption ofcertain materials which develop over time on the back side of the anode.If the anode is left unshielded, the organic chemical plating additivesare consumed at a significantly greater rate. With the shield in place,these additives are not consumed as quickly.

Wafer Rotor Assembly

The wafer rotor assembly 906 holds a wafer W for rotation within theprocessing chamber 904. The wafer rotor assembly 906 includes a rotorassembly 984 having a plurality of wafer-engaging fingers 979 that holdthe wafer against features of the rotor. Fingers 979 are preferablyadapted to conduct current between the wafer and a plating electricalpower supply and may be constructed in accordance with variousconfigurations to act as current thieves.

The various components used to spin the rotor assembly 984 are disposedin a fixed housing 970. The fixed housing is connected to a horizontallyextending arm 909 that, in turn, is connected to a vertically extendingarm. Together, the arms 908 and 909 allow the assembly 906 to be liftedand rotated from engagement with the bowl assembly to thereby presentthe wafer to the wafer conveying assembly 60for transfer to a subsequentprocessing station.

Alternative Lift and Tilt Mechanism

Turning now to FIG. 34, that figure shows an embodiment of a lift/tiltassembly 6000. The components of the lift/tilt assembly 6000 arepreferably formed from hard black anodized aluminum, although stainlesssteel may also be used. The lift/tilt assembly 6000 may be used to loadwafers into the interface modules 38,39 and may be used instead of, orin conjunction with, a wafer cassette turnstile 40 or 41 describedabove. Before the operation of the lift/tilt assembly 6000 is discussed,the component parts of the lift/tilt assembly 6000 will be described.

Referring again to FIG. 34, the lift/tilt assembly 6000 includes a nest6002 coupled to a linear guide 6004 that is driven by a motor 6006. Theterm “nest” generally indicates a platform on which a wafer bearingcassette may be loaded. The lift/tilt assembly 6000 includes a linearencoder LED assembly 6008 and a linear encoder CCD assembly 6010. Inaddition, the lift/tilt assembly 6000 preferably includes a protrusionsensor 6012, a protrusion sensor receiver 6014, and an H-bar sensor (notshown) located in the nest 6002. The nest 6002 moves between twoorientations generally described as wafer-horizontal and wafer-vertical.As shown in FIG. 34, the nest 6002 is in the wafer-horizontal position.

Turning now to FIG. 35, another view of the lift/tilt assembly 6000 isshown. A wafer cassette 6100, holding a number of wafers 6102, rests inthe nest 6002. As will be described in more detail below with respect tothe operation of the lift/tilt assembly 6000, the nest 6002 in FIG. 35is oriented in the wafer-vertical position.

Referring to FIGS. 36-38, three section views of the lift/tilt assembly6000 are shown. FIGS. 36-38 illustrate operation of the assembly atthree translational operating points and show the resultant positioningof the nest 6002 as it moves from a near wafer-vertical position (FIG.36) to a near wafer-horizontal position (FIG. 38). The linear guide 6004includes a fixed frame 6208 and a movable frame 62 10. The movable frame6210 may be implemented as any structure mounted on a moving portion ofthe linear guide 6004. For example, the movable frame 6210 may bemounted to a carriage that moves linearly under control of the motor6006. The linear guide 6004 may be implemented, for example, with alinear motion guide available from THK America, 200 E. Commerce Drive,Schaumburg, Ill. 60173.

Connected to the nest 6002 is a lever 6200 including a lever wheel orball bearing 6202 which rides on a guide, for example, ramp 6204. Theguide is generally implemented as a smooth surface over which the ballbearing 6020 may roll during transition between the wafer-horizontalposition and the wafer-vertical position. A torsion spring assembly 6206provides forcing bias on the nest 6002 which helps transition the nest6002 between a wafer-vertical position and a wafer-horizontal position(where the nest 6002 may be supported by a hard stop 6212) as will beexplained in more detail below. The ramp 6204 is mounted in a fixedposition on top of the fixed frame 6208 while the torsion springassembly 6206 is mounted on the movable frame 6210.

In operation, as noted above, a lift/tilt assembly 6000 is used to loadwafers into the interface modules 38, 39 and may reside behind powereddoors 35 or 36. During the loading or unloading process, the lift/tiltassembly 6000 returns to the wafer-vertical position shown in FIG. 35. Asensor connected to the powered doors 35, 36 may be used to inform thecontrol system 100 (FIGS. 14-21) that the powered doors 35, 36, are infact open, and that the lift/tilt assembly 6000 should not be allowed tomove (thereby providing a safety interlock mechanism).

For loading operations, the nest 6002 preferably returns to awafer-vertical position which is approximately 15 degrees above truevertical. The wafer-vertical position thereby holds the nest 6002 at asmall slope down which the wafer cassette 6100 may slide into acompletely loaded position. Furthermore, the preferred wafer-verticalposition helps eliminate a contaminant generating condition related tothe wafers 6102. Because the wafers 6102 fit loosely in the wafercassette 6100, the wafers 6102 tend to rattle when in a strictlyvertical orientation. When the wafers 6102 rattle, they tend to generateparticles that may contaminate the processing environment. Thus, thepreferred wafer-vertical position prevents the wafers 6102 from restingin a true vertical position and generating particles.

Referring again to FIG. 36-38, those figures show the motion of the nest6002 between its wafer-vertical position (FIG. 36) and itswafer-horizontal position (FIG. 38). The movable frame 6210 of thelinear guide 6004 moves linearly along a track under control of themotor 6006, a ball screw and linear bearings (not shown). The motor 6006generally includes a rotary encoder, typically an optical encoder, thatproduces a relative encoder output including a predetermined number ofpulses (for example, 2000) per motor revolution. The pulses indicate thenumber of revolutions (or fractions of revolutions) through which themotor has turned. The pulses may therefore be converted to a lineardistance by taking into account the coupling between the motor 6006 andthe linear way 6004. The pulses may be fed back to the control system100, or may be processed by a local microcontroller which coordinatesthe movement of the linear guide 6004.

In addition to the relative encoder output that the motor produces, thelift/tilt assembly 6000 may optionally include a linear encoder LEDassembly 6008 and a linear encoder CCD assembly 6010 which operatetogether as an linear absolute encoder. Referring again to FIG. 35, theLED assembly 6008 is shown and includes a series of LEDs 6104 andcorresponding light transmission slits 6106. The linear encoder CCDassembly 6010 includes a CCD module 6110 and associated CCD controlcircuitry 6108.

Each individual LED 6104 produces a light output which is directedthrough a corresponding slit 6106. Each slit 6106 only allows light topass through that is produced by its corresponding LED, and to that endmay, for example, be 15 mils or less in width. The LEDs 6104 are mountedon the fixed frame 6208, while the linear encoder CCD assembly 6010 ismounted on the movable frame 6210. The CCD module 6110 moves along apath underneath the slits 6106 and therefore may detect light producedby the LEDs 6104. Therefore, as the moveable frame 6210 translates up ordown the linear way 6004, the CCD control circuitry 6010 may monitor thenumber and position of the light sources it detects and may providefeedback as to the absolute vertical position of the moveable frame6210. Commercially available CCD modules provide sufficient resolutionto determine the vertical position of the moveable frame 6210 topreferably in a range of less than 10 mil resolution. The control system100 may use feedback from the CCD control circuitry 6010, for example,as a double check against the rotary encoder output produced by themotor 6006.

As the moveable frame 6210 advances up the linear guide 6004, the nest6002 moves up with the torsion spring assembly 6206 above from the ramp6204. The torsion spring exerts a force on the nest 6002 and lever 6200,causing the nest 6002 to rotate around the torsion spring assembly 6206and into the wafer-horizontal position. During the transition from thewafer-vertical position to the wafer-horizontal position, the ballbearing 6202 and lever 6200 ride on the ramp 6204 which helps ensure asmooth transition between the two positions. When the nest 6002 reachesthe wafer-horizontal position, a hard stop 6212 is provided thatprevents further rotation of the nest 6002 around the torsion springassembly 6206.

It is noted that other devices may be used to induce rotational movementof the nest 6002. For example, a nest motor may produce torque on ashaft rigidly connected to the nest 6002 to cause it to rotate betweenthe wafer-vertical and wafer-horizontal orientations. The torqueproducing nest motor may operate under general program control of thecontrol system 100 to produce rotation in the nest 6002 as the moveableframe 6210 translates.

The torsion spring in the torsion spring assembly 6206 provides theforce required to lift a wafer cassette 6100, including wafers 6012,from the wafer-vertical position to the wafer-horizontal position. Tothat end, the torsion spring is preferably formed from music wire, butmay also be formed from stainless steel. When the motor 6006 activatesto draw the movable frame 6210 back down the linear way 6004, the nest6002 rotates in the opposite direction around the torsion springassembly 6206. The level 6200 and ball bearing 6202 move smoothly alongthe ramp 6204 in the opposite direction to return the nest 6002 to thewafer-vertical position. At the wafer-vertical position, the lever 6200provides a stop that holds the nest 6002 at approximately 15 degreesfrom true vertical (FIG. 36). It is noted that linear movement in thelinear guide 6004 accomplishes both translational and rotationalmovements in the nest 6002.

Additional sensors may be provided on the lift/tilt assembly 6000 toprovide feedback regarding the status of the nest 6002 and the wafercassette 6100. As noted above, an H-bar sensor may be located in avariety of positions in the nest 6002. A wafer cassette 6100 generallyincludes two registration bars of vertical length and a registrationcross bar of horizontal length. The bars are collectively referred to asan “H-bar”. The H-bar sensor may be implemented as an optical sensor andreceiver pair or as a mechanical switch sensor that indicates when theH-bar, and therefore a wafer cassette 6100, is present in the nest 6002.An optical H-bar sensor may operate, for example, by providing anoptical transmission and reception path which is broken by an H-bar on aloaded wafer cassette 6100, while a mechanical H-bar sensor may operateby providing a mechanical switch that is triggered when the wafercassette 6100 is inserted in the nest 6002.

Because each wafer cassette manufacturer may control the location of theH-bar and because the wafer cassette may vary in construction betweenmanufacturers, the nest 6002 may be configured with different H-barassemblies that accept the wafer cassettes 6100 of variousmanufacturers. The H-bar sensor, in turn, is not restricted to anyparticular position on the nest 6002, but may be implemented as anyoptical or mechanical sensor positioned to detect the H-bar or otherfeature on a particular wafer cassette 6100. FIG. 39 shows one exampleof an H-bar assembly 6500.

The H-bar assembly 6500 includes a horizontal track 6502, a firstvertical track 6504, and a second vertical track 6506. The H-barassembly 6500 also includes an optical sensor 6508 and an opticalemitter 6510. An H-bar on a wafer cassette 6100 fits into the horizontaltrack 6502 and the vertical tracks 6504, 6506. As shown in FIG. 39, theoptical emitter 6510 is positioned to emit energy along the horizontaltrack 6502. The optical sensor is positioned across the horizontal track6502 to receive the emitted energy. The optical sensor 6508 maytherefore detect the presence or absence of an H-bar of a wafer cassette6100 by determining whether it is receiving energy emitted by theoptical emitter 6510. The H-bar assembly may be mounted to the nest6002, for example, across the area 6600 shown in FIG. 40.

The lift/tilt assembly 6000 may also provide a tilt position sensor. Asnoted above, the torsion spring assembly 6206 provides the forcerequired to move the wafer cassette 6100 from a wafer-verticalorientation to a wafer-horizontal position. The tilt position sensorprovides feedback that indicates when the nest 6002 has reached thewafer-horizontal position. FIG. 40 shows one possible implementation ofa tilt sensor on a nest 6002.

FIG. 66 shows the top side 6602 of the nest 6002 and the bottom side6604 of the nest 6002 and a tilt sensor 6604. The tilt sensor may, forexample, connect to the bottom side 6604 at location 6606. The tiltsensor 6604 includes an emitter 6610 and a sensor 6612. An interrupterflag 6614 is mounted on the moveable frame 6210. As shown in FIG. 66,the emitter 6610 and the sensor 6612 are placed so that an unbrokenoptical path exists between the transmitter and receiver while the nest6002 is rotated out of the wafer-horizontal orientation. The emitter6610 and the sensor 6612 are also placed on the nest 6002 such that whenthe nest 6002 rotates into the wafer-horizontal orientation, theinterrupter flag 6614 connected to the moveable frame 6210 breaks thepath between the emitter 6610 and the sensor 6612.

A tilt sensor may also be implemented as a mechanical switch located onthe hard stop 6212. The mechanical switch may then be triggered by thenest 6002 coming into the wafer-horizontal position at the hard stop6212. Feedback from either the mechanical switch or the optical sensormay be used to determine when the torsion spring assembly 6206 iswearing out, or has failed altogether (for example, the control system100 may detect that after a sufficient number of motor 6006 revolutions,that the tilt sensor does not indicate wafer-horizontal position for thenest 6002).

Referring again to FIG. 35, that figure illustrates the positions of aprotrusion sensor 6012 and a protrusion sensor receiver 6014. Theprotrusion sensor 6012 houses an emitter, for example an opticalemitter, that transmits a beam down to a protrusion sensor receiver6014. As shown in FIG. 35, the protrusion tube sensor 6012 is orientedalong the right hand side of the lift/tilt assembly 6000. FIG. 34,however, illustrates that a protrusion sensor 6012 may also be orientedalong the left hand side of the lift/tile assembly 6000. The left handorientation includes a left hand protrusion sensor receiver 6014provided underneath the protrusion sensor 6012 (FIG. 34).

Referring again to FIG. 35, the protrusion sensor 6012 may detect whenwafers 6102 are improperly seated in the wafer cassette 6100. Forexample, wafers that have become dislodged and that therefore extend outof the wafer cassette 6102 will block the sensor receiver 6014. Becausedislodged wafers may catch on an exposed surface during the lift/tiltactuation 6000, the possibility exists that a dislodged wafer may bebroken by vertical movement of the moveable frame 6210. Thus, when theoutput of the sensor receiver 6104 indicates a blocked condition, thecontrol system 100 may respond, for example, by generating an errordisplay, or by directing the wafer transport units 62, 64 to avoidprocessing the dislodged wafer. The control system 100 may also respondby returning the nest 6002 to the wafer-vertical position in an attemptto move the dislodged wafer back into place in the wafer cassette 6100.Note that, in general, the protrusion sensor 6012 provides the mostmeaningful feedback when the nest 6002 is in the wafer-horizontalorientation.

Each of the sensors described above may be connected to the controlsystem 100 which may in response exercise intelligent control over thelift/tilt assembly 6000. It will be recognized that the preciseplacement of the sensors may vary widely while allowing the sensors toperform their intended functions. Thus, for example, it may be possibleto mount the protrusion sensor receiver on a portion of the moveableframe 6210 rather than the nest 6002. Furthermore, an additional sensorsystem, a laser mapping unit, may be provided for indexing the wafers,or absence of wafers, in a wafer cassette 6100.

Referring to FIG. 41, a laser mapping system 6700 in shown that includesoptical transmitters 6702 and 6704 and optical receivers 6706 and 6708.The optical receivers 6706 and 6708 are placed behind an opening 6710 inthe nest 6002. The optical receivers 6706 and 6708 and the opticaltransmitters 6702 and 6704 may be mounted on a fixed structure 6712supported independently of the lift/tilt assembly 6000.

The optical transmitters 6702 and 6704 emit radiation, for example atvisible or infrared wavelengths, along the nest 6002 and through theopening 6408. The optical receivers 6706 and 6708 produce outputsresponsive to the amount of emitted radiation they detect. The nest 6002moves vertically through the laser mapping system 6700 during theoperation of the laser mapping system 6700. In particular, after thenest 6002 has reached the wafer-horizontal position, the moveable frame6208 may continue to move the nest 6002 (which rests against the hardstop 6212) vertically.

As the nest 6002 continues to move vertically, a laser mapping functiontakes place during which each of the wafers 6012 passes, in turn, infront of the optical transmitters 6704 and 6706. The radiation emittedby the optical transmitters 6705 and 6706 is therefore alternatelyprevented and allowed to reach the optical receivers 6706 and 6708. Thecontrol system 100 may, therefore, monitor the optical receiver 6706 and6708 outputs, the motor 6006 rotary encoder output, and optionally thelinear encoder CCD assembly 6010 outputs to determine the presence orabsence of wafers 6012 and the position of the present or absent wafers6012 in the wafer cassette 6100. A single optical transmitter andreceiver pair is sufficient to perform the laser mapping function,although additional individual optical transmitters, such as the opticaltransmitter 6704, may be provided to check exclusively for the presenceof wafers or to check exclusively for the absence of wafers, forexample.

After the laser mapping procedure has completed, the control system 100may continue to raise the nest 6002 above the optical transmitters 6702and 6704 so that the wafer transport units 62, 64 can access individualwafers 6012. FIG. 42 illustrates the nest 6002 in a position above thelaser mapping system 6700. The control system 100 may then instruct thewafer transport units 52, 54 to operate on the wafers 6102 that thelaser mapping system has detected and adjust the height of the nest 6002so that the wafer transport units 52,52 may access individual wafers6012. The control system 100 may also instruct the wafer transport units52, 54 to skip gaps in wafers 6102 that may be present in the wafercassette 6100 or may instruct the wafer transport units 52, 54 to usegaps in the wafer cassette 6100 to store processed wafers.

Numerous modifications may be made to the foregoing system withoutdeparting from the basic teachings thereof. Although the presentinvention has been described in substantial detail with reference to oneor more specific embodiments, those of skill in the art will recognizethat changes may be made thereto without departing from the scope andspirit of the invention as set forth in the appended claims.

What is claimed:
 1. A workpiece processing apparatus comprising: aninput section including a carrier transfer apparatus disposed to acceptat least one carrier that is adapted to carry a plurality of workpieces,the carrier transfer apparatus being automatically linearly movablebetween at least a carrier loading position in which the at least onecarrier is received at a first vertical level with the workpieces in afirst orientation with respect to horizontal, and a workpiece processingposition in which the at least one carrier is re-oriented to present theworkpieces disposed therein in a second orientation with respect tohorizontal at a second vertical level; a processing section having aplurality of processing stations for processing the workpieces; and aworkpiece transfer apparatus disposed in the processing section toaccept the workpieces in the second orientation at the second verticallevel and provide them to one or more of the processing stations in theprocessing section.
 2. A workpiece processing apparatus as claimed inclaim 1 wherein the workpieces are oriented so that they are generallyhorizontal when the carrier is in the workpiece processing position andso that they are generally vertical when the carrier is in the carriertransfer position.
 3. A workpiece processing apparatus comprising: aninput section including a carrier transfer apparatus disposed to acceptat least one carrier that is adapted to carry a plurality of workpieces,the carrier transfer apparatus being automatically movable between atleast a carrier loading position in which the at least one carrier isreceived at a first vertical level with the workpieces in a firstorientation with respect to horizontal, and a workpiece processingposition in which the at least one carrier is re-oriented to present theworkpieces disposed therein in a second orientation with respect tohorizontal at a second vertical level; a processing section having aplurality of processing stations for processing the workpieces; and aworkpiece transfer apparatus disposed in the processing section toaccept the workpieces in the second orientation at the second verticallevel and provide them to one or more of the processing stations in theprocessing section wherein the second level is higher than the firstlevel.
 4. A workpiece processing apparatus as claimed in claim 3 whereinthe processing section includes at least one electroplating station. 5.A workpiece processing apparatus as claimed in claim 4 wherein theprocessing section includes at least one electroplating station forplating one or more of the workpieces with copper.
 6. A workpieceprocessing apparatus as claimed in claim 5 wherein the workpiecetransfer apparatus comprises: a robot arm adapted to handle single onesof said workpieces; a linear drive mechanism supporting the robot armand driving the robot arm along a linear track to a position proximatethe further carrier transfer apparatus to allow the robot arm to insertindividual processed workpieces into the further carrier.
 7. A workpieceprocessing apparatus as claimed in claim 4 and further comprising: atleast one further carrier disposed to receive processed workpieces fromthe workpiece transfer apparatus with the workpieces in the secondorientation; a further carrier transfer apparatus disposed to accept theat least one further carrier, the further carrier transfer apparatusbeing automatically movable between a workpiece loading position inwhich the processed workpieces are received from the workpiece transferapparatus in the second orientation at a third vertical level, and acarrier removal position in which the at least one further carrier isrotated about a generally horizontal axis to place the workpiecesdisposed therein in the first orientation at a fourth vertical level. 8.A workpiece processing apparatus as claimed in claim 7 wherein theworkpieces are oriented so that they are generally horizontal when thecarrier is in the workpiece loading position and so that they aregenerally vertical when the carrier is in the carrier removal position.9. A workpiece processing apparatus as claimed in claim 7 wherein thethird level is higher than the fourth level.
 10. A workpiece processingapparatus as claimed in claim 7 wherein the further carrier transferapparatus is disposed in an output section that is separated from theinput section.
 11. A workpiece processing apparatus as claimed in claim7 wherein the input section and the output section are disposed in aside-by-side relationship.
 12. A workpiece processing apparatus asclaimed in claim 3 wherein the workpiece transfer apparatus comprises: arobot arm adapted to handle single ones of said workpieces; a lineardrive mechanism supporting the robot arm and driving the robot arm alonga linear track to a position proximate the carrier transfer apparatus toallow the robot arm to remove individual workpieces from the carrierthat has been moved to the workpiece processing position by the carriertransfer apparatus.
 13. A workpiece processing apparatus as claimed inclaim 3 wherein the carrier transfer apparatus comprises an elevator,the elevator comprising: a linear guide comprising a fixed frame and amoveable frame; a carrier nest rotatably connected to the moveableframe, the nest rotating the carrier as it is moved between the carrierloading position and the workpiece processing position; a drive coupledto automatically move the movable frame of the linear guide.
 14. Aworkpiece processing apparatus as claimed in claim 13 wherein themovable frame of the linear guide is disposed about and at leastpartially surrounds the fixed frame.
 15. A workpiece processingapparatus as claimed in claim 14 and further comprising a cammingmechanism disposed to rotate the carrier nest about a generallyhorizontal axis to place the carrier and corresponding workpieces in theappropriate horizontal orientation for the carrier loading and workpieceprocessing positions, the camming mechanism being actuated by movementof the movable frame.
 16. A workpiece processing apparatus as claimed inclaim 3 wherein the carrier transfer apparatus comprises: a turnstileconfigured to support the workpiece carrier and rotate the carrier abouta generally horizontal axis to place the carrier and correspondingworkpieces in the appropriate horizontal orientation for the carrierloading and workpiece processing positions; an elevator adjacent saidturnstile and configured to move the workpiece carrier verticallybetween the first and second vertical levels; the workpiece carrierbeing transferred between the turnstile and the elevator.
 17. Aworkpiece processing apparatus as claimed in claim 16 wherein theworkpiece carrier is transferred between the elevator and the turnstilewhen the elevator is positioned proximate the carrier loading position.